Add missing static on file-scope variable
diff --git a/library/psa_crypto_slot_management.c b/library/psa_crypto_slot_management.c
index 4e193b5..0b4399f 100644
--- a/library/psa_crypto_slot_management.c
+++ b/library/psa_crypto_slot_management.c
@@ -50,7 +50,7 @@
unsigned key_slots_initialized : 1;
} psa_global_data_t;
-psa_global_data_t global_data;
+static psa_global_data_t global_data;
/* Access a key slot at the given handle. The handle of a key slot is
* the index of the slot in the global slot array, plus one so that handles